The sea hare, a marine aplysiid gastropod mollusk, is an important animal in neurophysiological, immunological and toxicological research. Current investigations are hampered by the absence of information about the natural life history of the animal. To date, no aplysiid has ever been reared from egg to adult form under controlled conditions. Dr. John Bardach and his associates at the Hawaii Institute of Marine Biology have observed the metamorphosis of an aplysiid in their laboratory. The applicant has been invited by Dr. Bardach to investigate the conditions under which this metamorphosis has been taking place. A small grant is required to support the initial stages of this project. We propose to verify Dr. Bardach's preliminary observations of metamorphosis of the aplysiid, Stylocheilus longicauda, and to specify the characteristics of the milieu in which the animals develop to maturity. These conditions will be replicated at the HIMB, the Lerner Marine Laboratory (Bimini) and the American Museum of Natural History for the rearing of Aplysia dactylomela, a species that has been studied by the applicant for the past eight years. The development of techniques for rearing these animals in the laboratory will make them easily available for research. Descriptions of the morphological, physiological and behavioral development of the sea hare will be obtainable under controlled conditions. This information will help to elucidate the ecological and behavioral adaptations of the species. A laboratory source of sea hares will counteract possible destruction of local populations. In addition, laboratory rearing will provide genetically defined subjects, and will make possible the analysis of the relationship between developmental phenomena and the physiological and behavioral characteristics of the adult.